Duplex fluid braking system



March 23, 1937. w. F. OLIVER DUPLEX FLUID BRAKING SYSTEM Filed Dec. 28, 1935 N h 3 a: mu on ok um /m=/ 02 o! J A m. 8 Ne W s v! 3 3 h. 0% NM w\\ me Q N Q mm E. .g Q wQ vQ om mm. Ln Wu 9% wk on Q WM. mm Wm Q Ms R mQ 1N VENT OR.

Patented Mar. 23, 1937 UNITED STATES I 2,074,416 'ncrmx'rnnm anama srs'rau MM 1-. Oliver, Detroit, Mich, assignor to Bydraulic Brake ompany,.Deti-oi t,- Mich a cotin itation of California Application December 28,1935, Serial No. 56,489

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This invention relates to brakes for motor veo hicles, and-more particularly to a duplex fluid braking system. I

I Theinvention comprehends independent fluid pressure systems and means for, compensating for a differential of pressure in the systems.-

- An object of the invention is to provide afluid pressure braking system including a duplex fluid pressure producing device. Another object of theinvention is'to provide separate fluid pressure braking systems including an actuating device connected to operate thesystems in unison to compensate for a difleren v tial oi pressure in the-systems and to maintain one of the systems operative in the event of iailure of the other system. a Other objects of the invention will appear from the following description taken in connection with the drawing which forms-apart of this s ecification, and in which,- r

Fig. 1 is a schematic view of a duplex fluid pressur; braking system embodying the invention; Fig. 2 is a vertical sectional view of a fluid pressure producing device. g A

Referring to the drawinglfor more specific details of the invention, It) represents a reservoir including two separate compartments orcontainers' l2 and I4 provided withfilling openings l6 and i8 which may beclosed by plugs 2 6:and 22 having openings 24 and 26 for venting the containers l2 and M to the atmosphere. 'A compoundcylinder 28 formed at the base of the reservoir includes a large 5 small cylinder 32. The cylinders are arranged concentrically with relationtmone another and are divided by an apertured diaphragm 34. The cylinder 30 has ports @6 and 36, providing communicationsbetween the cylinder and the con- 0 tainer 12 of the reservoir, and a discharge port 46 controlled as by a two-w, y valve 42. A fluid pressure delivery pipe or conduit 44 connectedto thevalve 42 has branches connectedrespectively to fluid pressure factuated motors 46 for actuating 45 the friction elements or brakes.

' Similarly, the cylinder 32 as ports 46 and 50 providing communications between the cylinder and the container-l4 of the reservoir, adischarge port 62 controlled by aItwo-way' valve 64,- anda adjacent to the diaphragm 34." A fluid pressure delivery D196 Or conduit 68 connected to the valve 64 has branches connected respectively to fluid pressure actuated motors 60' for the ac-' ,tuation of friction elements'or brakes. I Themotors 46 aid 66 are arranged in pairs, one

' has a sectionreduced in diameter to provide, in

head of the piston is provided with a plurality of cylinder 36 and a seepage of fluid from the cylinder 92 providing a terior of thesleeve and the cylinder Sll. A pis- -'against displacement by a spring I interposed PATENT OFFICE pair for the actuation of the brakes associated with the front wheels of a vehicle, and the other pair for actuating the brakes associated with the rear wheels of the vehicle. The brakes may be.

sociated therewith. interchangeable friction elements or shoes 66 pivoted on the backing plate, and a motor corresponding to the motors 46 and 60 arrangedon-the'backing plate and operative to.- move the shoes into engagement with the drums against the resistance of aretractile spring 68 connecting the shoes of the respective brakes.

A-piston I0 reciprocable in thecylinder 30 is held against displacement by a washer I2 seated on an'annular'shoulder in the open end of the cylinder and secured in position by a retaining ring 14 seated in a continuous groove in the wall of the cylinder. The skirt oi the piston has a groove for the reception of a leak-proof cup '16 which provides against seepage of fluid from the cylinder past the piston, and the body of the piston conjunction with the wall of the cylinder, a chamber l8-communicating with the container i2 0! the reservoir by way of the port 36. The

spaced openings or ports 86 providing communications between the annular chamber 18 and that portion of the cylinder forward of the piston.

A sleeve 82 formed concentrically on the head of the piston is received by the aperture in the diaphragm 34, and a collapsible leak-proof cup 84 slipped over the sleeve 82 seats on the head of the piston for control of the ports 80. A leak-proof cup 66, also slipped on the sleeve, seats on the diaphragm 34 to provide against 30 to the cylinder 32; and a spring 68 interposed between the cups serves to retain them in position and 40 also to return thepistonto its retracted position.

The forward end of the sleev .62 is closed by anapertured head 96; and the sleeve has a port comm cation between the inton 94, reciprocablein the sleeve, has a concentric stem 96 rec ived by the aperture in the head 96, and a leak-proof cup 96 onits head is held between the cup and the head of the piston 10. 60

A piston I62, reciprocable "in the cylinder 32, seats on the diaphragm 34 when in retracted position. The skirtof the piston carries a leakprooi washer I04 providing against seepage of fluid from the cylinder past the piston. The body 55 the piston. A collapsible leak-proof cup IIO seat-.

ed on the head of the pistoncontrols the ports I I08. This cup is provided with a concentric opening II2, the object of which will hereinafter appear, and a spring I I4 interposed between the cup and the two-way valve 64 serves to retain the cup and the valve in position and also to return the piston I02 to its retracted position.

-The body of the piston is axially bored to provide a chamber II6 having a port II8 registering with the opening H2 in the collapsible leak-proof cup IIO to provide for communication between the chamber II 6 and the cylinder 32. A head I20 threaded in the chamber I I6 abuts the sleeve 82 and the head 80 of the sleeve 82. The head I20 has an aperture registering with the aperture in the head 90 of the sleeve 82. A piston I22 reciprocable in the chamber II6 has a concentric stem I24 received by the aperture in the head I20 and abuts the stem 96 of the piston 84, of the by a spring I 28' imposed between the cup and the back of the head of the piston I 02. The tensile strength of the spring I28 is the same as the tensile strength of the spring I00, so as to normally balance the pistons 94 and I22.

The piston I0 has a recess I30 for the reception of one end of a thrust pin I32, the other end of which is provided with a coupling I34 connected as by a flexible boot I 36 to the open end of the cylinder 30 for the exclusion of dust 40 and other foreign substances from the cylinder,

and a leak-proof cup I26 on the head and a rod I88 connects the coupling I34 to a foot pedal lever I40 pivoted on a suitable support I42 and connected by a retractile spring I44 to a fixed support I46.

45 In a normal operation, when the foot pedal lever I40 is depressed to apply the brakes, force is transmitted therefrom and the thrust ing in moving stroke,

through the rod J38 pin I34 to the piston 'I0,.result-' the piston 10' on itscompression the piston I0 carrying'with it the piston During the initial movement of these pistons on their compression strokes, the collapsible leakproof cups 84 and 0 on the heads of the re- 5 5 spective pistons close the ports 38 and 50 so as to'cut oil. communication between the cy inders 30 and 32 and the respective containers I2 and I4 of the reservoir," and upon further anovement of the pistons I0 and I02 on their compression strokes fluid in the cylinders 30 and 32 is displacedtherefrom past the two-way valves 42 and .64, through the fluid ,pipes or conduits 44 and 58 and their respective branches, into the fluid pressure actuated motors 46 and 60, energizing these motors with the resultant movement of the shoes 66 into engagement with the drums 64 against the resistance of, tractile springs 68.

I .Uponrelease-of the foot pedal lever I43 the (0. retractile spring II4 returns this lever to its normal position and retracts the thrust pin I38. As

the 'foot pedal lever moves to its normal position, the'pis'tons I0 and I02 return to'fitheir-retracted positions under the influence of the springs 88 75 and H4, and as the pistons move to their repiston I22'is held against displacement pistons.

pressure delivery tracted positions a partial vacuum is created in the cylinders 30 and 32 with the result that fluid is drawn from the containers I2 and I4 of the reservoir through the ports 86' and 48, the annular chambers ports 80 and I08 in the heads of the pistons I0 and I02, past the collapsible cups 84 and M0 on the heads of the pistons,into those portions of the respective cylinders30 and 32 forward of the pistons. During this movement fluid is returned to the cylinders tors 46 and 60 under the influence of ,retractile springs 68 connecting the shoes of the respective brakes.

Under normal conditions of operation the pressure developed in the respective cylinders 30 and ,32, and the motors 46 and 60, respectively connectedto these cylinders, is substantially equal, and thus the friction elements of the respective brakes connected to these motors are actuated with equal force and efiect. I

Due to the size of the sleeve 82 in the cylinder 30, the cylinders 30 and 32 have the same capacity, and because of an equalized pressure in the'cylinders 30 and 32, and in the sleeve 82 and the chamber II6 communicating respectively with these cylinders, there is no perceptible movement of the pistons 94 and I22. However, should there occur an unequal pressure in the cylinders 30 and 32, due to leakage or other causes, the pistons 84 and I22 immediately shift to compensate for the diiferential-in pressure in the cylinders to the end that the brakes may be actuated with substantially equal effect; and should the differential of pressure in the respective cylinders 30 and 32 be of such magnitude as to'render one entirely ineifecfore, to be limited only as indicated by the scope of the appended claims.

Having thus'desoribed the various features of the invention, what I claim as new and desire to secure by Letters Patent is,

1. A fluid pressure producing device comprising apair of cylinders arranged concentrically to one another, a piston reciprocable in each of the 0371- inders, a single actuating means-for both of the and cooperative devices carried by the pistons for equalizing pressure in the cylinders.

2. A fluid pressure producing-device comprising a pair of cylinders arranged concentrically to one another, a piston reciprocable in each of the cylinders, a single actuating means for both pistons,

and shiftable cooperative members carried by the pistons for equalizing pressure in the cylinders.

.. 3. A fluid pressure producing device comprising a pair of cylinders arranged concentrically to one another, a piston reciprocable in each of the cylinders, a single actuating means for both pistons,

a sleeve on one of the pistons. a chamber in the other piston, and opposed pistons reciprocable in the sleeve and chamber. for equalizing pressure in a pair of cylinders arranged concentrically. to one another, pistons neciprocable in each of the cylinders, a single actuating means for both pistons, a chamber in one of the pistons, a sleeve on the 18 and I06, and through the 30 and 32 from the mo other piston commu eating withthe chamber, and opposed spring-pressed pistons reciprocable in the chamber and sleeve respectively for equalizing pressure in the cylinders.

5. A fluid pressure producing device comprising a pair of cylinders of different diameters arranged concentrically to one another, a piston reciprocable in each of the cylinders, a single actuating means for both pistons, a sleeve on the piston in the larger cylinder having a port communicating with the larger cylinder, a chamber in the piston in the smaller cylinder having a port communicating with the smaller cylinder, and cooperative pistons reciprocable in the sleeve and chamber.

6. A fluid pressure producing device comprising a pair of cylinders of different diameters arranged concentrically to'oneanother, a piston reciprocable in each of the cylinders, a single actuating means for both pistons, a sleeve on the piston in the larger cylinder having a port communicating with the larger cylinder, said sleeve abutting der, a chamber in the piston in cylinder having a port communicating with the smaller cylinder, a spring-pressed piston in the sleeve, a spring-pressed piston in the chamber, the pistons in the sleeve and chamber cooperating with one another to equalize pressure in the cylinders.

'7. A fluid pressure producing device comprising a reservoir having cylinders of different diameters arranged'concentrically to one another at the base of the reservoir, the larger cylinder being supplied from one of the compartments and the smaller cylinder being supplied from the other compartment, a single actuating means for both pistons, a sleeve on the piston in the larger cylinder having a port providing a communication between the sleeve and the larger cylinder, said sleeve abutting the piston in the smaller cylinder, a chamber in the piston in the smaller cylinder having a port providing a communication between the I another at the two compartments, a pairot chamber and the smaller cylinder, a springpressed piston in the sleeve, and a spring-pressed piston in the chamber-cooperating with the piston in the sleeve to equalize pressure in the cylinders.

8. In a braking system, a fluid pressure producing device comprising a reservoir including two compartments, a pair of cylinders of different diameters arranged concentrically to one base of the reservoir, the larger cylinder having ports providing communications betweenone of the compartments and the cylinports providing 1 der, the small cylinder having communications between the small cylinder and the other compartment of the reservoir, fluid pressure actuated motors connected to each of the cylinders, a piston reciprocable in each of the cylinders, a single actuating means for both pistons, and s 'ftable means carried by the pistons for equalizing pressures in the cylinders;

9. In a braking syste d pressure producing device includi a reservoir having two compartments, a pair ylinders of different diameters arranged concentrically to one another at the base of the reservoir, one of the cylinders being suppliedwith fluid from one of the compartments and with fluid from the other compartment, pressure actuated motors operatively connected to each of the cylinders, a piston reciprocable in each of the cylinders, a single actuating means for both of the pistons, a sleeve on the piston in the larger cylinder provided with a port communicating with the larger cylinder, a chamber in the piston in the smaller cylinder provided with a,port communicating with the smaller cylinder, a spring-pressed piston in the sleeve, and

' a spring-pressed piston in the chamber, the piston in the sleeve and the piston in the chamber cooperating with one another to equalize pressures in the cylinders.

- WALLACE F. OLIVER. 

